Apprentice guide
Ang method sa likod ng cable size, ipinaliwanag hakbang-hakbang kasama ang mga numerong ipinapakita.
- 5 min basahinBuilder's pole: supply, RCDs and cord lengthsA builder's pole for a house build, worked to AS/NZS 3012:2019. The supply it may take, the 30 mA RCDs, the Table 1 cord lengths and the test intervals.
- 5 min basahinOhm's law on a 3 kW water heater elementWork the current and working resistance of a 3 kW, 230 V water heater element with Ohm's law, why a cold meter reading is lower, then a 9 kW three-phase bank.
- 5 min basahinRCD tripping with no fault: add up the leakageAn RCD on a home office and kitchen trips with no fault found. Add up the standing leakage, check it against a third of 30 mA, and split it over two RCDs.
- 3 min basahinVoltage drop single phase vs three phaseThe same 6 mm² cable at 32 A over 50 m, worked on a three phase supply and on a single phase supply, with both drops, both percents and both run limits.
- 3 min basahinA test sheet for a house boardA test sheet for a six-circuit New Zealand house board, with the tests in the AS/NZS 3017 order and the limit for each reading, then the Australian sheet.
- 3 min basahinReading the wiring in an older houseA 1970s New Zealand house with yellow actives, a green earth and a black neutral. What each colour can be, what may stay, and how to sleeve new terminations.
- 4 min basahinConsumer mains fault withstand for 16 mm² copperA domestic 6 kA fault cleared in 10 milliseconds against 16 mm² copper PVC mains, giving a 5.41 mm² minimum size and a 17.76 kA adiabatic withstand.
- 3 min basahinDC isolator rating for a 10 kW solar arrayRate the d.c. isolator and size the frame earth for a four-string domestic array. Check one data sheet that passes and one that fails per pole.
- 1 min basahinHow far can 1.5 mm² run on a 10 A circuit?1.5 mm² copper on a 10 A curve C circuit can run 34.85 m before it reaches the 5 % voltage drop limit. The fault loop alone would allow 82 m.
- 1 min basahinHow far can 4 mm² run on a 25 A circuit?4 mm² copper on a 25 A curve C circuit can run 41 m at full load before it reaches the 5 % voltage drop limit. At 20 A of load it can run 51.25 m.
- 1 min basahinHow many amps can 1.5 mm² cable carry?1.5 mm² copper multicore PVC cable carries 16 A enclosed in air at 30 °C in NZ, so it takes a 16 A breaker. Clipped direct, it carries 17 A.
- 1 min basahinHow many amps can 2.5 mm² cable carry?2.5 mm² copper multicore PVC cable carries 23 A enclosed in air at 30 °C in NZ, so a 20 A breaker protects it. Grouped with two circuits, it carries 16.1 A.
- 1 min basahinHow many amps can 2.5 mm² carry in Australia?2.5 mm² copper multicore PVC cable carries 20 A enclosed in air at 40 °C on AS/NZS 3008.1.1:2025, exactly a 20 A breaker. Clipped direct, it carries 22 A.
- 1 min basahinHow many amps can 6 mm² cable carry?6 mm² copper multicore PVC cable carries 38 A enclosed in air at 30 °C in NZ, so it takes a 32 A breaker. At 40 °C it carries 33.44 A.
- 1 min basahinHow many 2.5 mm² cables fit in 20 mm conduit?Six single-core 2.5 mm² cables fit in 20 mm conduit at 34.56 % fill, inside the 40 % limit of AS/NZS 3000 Appendix C. A seventh takes it to 40.32 %.
- 1 min basahinHow many lights on a 10 A circuit?In a home, AS/NZS 3000 Table C9 fills a 10 A circuit at 20 lighting points. A 21st point takes the sum over the circuit-breaker rating.
- 1 min basahinHow many power points on a 20 A circuit?In a home, AS/NZS 3000 Table C9 fills a 20 A circuit at 20 single 10 A socket-outlets. A non-domestic installation counts each one at twice that.
- 1 min basahinMaximum Zs for a 16 A curve C breakerAS/NZS 3000 Table 8.1 allows a maximum Zs of 1.92 Ω for a 16 A curve C breaker at 230 V. A 30 m run of 2.5 mm² cable reads 0.89 Ω.
- 1 min basahinMinimum cable size for a lighting circuitAS/NZS 3000 Table 3.3 sets a minimum of 1 mm² copper for circuits other than socket-outlets, lighting included. The load and the run often need more.
- 1 min basahinMinimum cable size for power pointsAS/NZS 3000 Table 3.3 sets a minimum of 2.5 mm² copper for a socket-outlet circuit. An exception can allow less, under conditions you must meet first.
- 3 min basahinStarting a loaded conveyorA 22 kW conveyor that needs 120 % torque to break away. Why star-delta and a soft starter will not start it, and what a drive or autotransformer does.
- 1 min basahinVoltage drop on 2.5 mm² over 30 m20 A on 2.5 mm² copper over 30 m drops 10.81 V, which is 4.7 % at 230 V and close to the 5 % limit. The run can reach 31.91 m.
- 1 min basahinWhat size cable for a 25 A circuit?A 25 A single-phase circuit takes 4 mm² copper on a typical NZ route, with 29 A of derated capacity. 2.5 mm² stops at 23 A, short of the breaker.
- 1 min basahinWhat size cable for a lighting circuit in NZ?A 10 A lighting circuit in New Zealand takes 1.5 mm² copper over 30 m, with 16 A of derated capacity and a 4.3 % drop. A 16 A circuit takes 2.5 mm².
- 1 min basahinWhat size cable for power points in Australia?A 20 A power point circuit in Australia takes 2.5 mm² copper on AS/NZS 3008.1.1:2025, rated 20 A enclosed in air at 40 °C. Grouping pushes it to 6 mm².
- 1 min basahinWhat size cable for power points in NZ?A 20 A power point circuit in New Zealand takes 2.5 mm² copper enclosed in air, with 23 A of derated capacity. Ceiling insulation moves it to 4 mm².
- 4 min basahinMotor circuit for a 15 kW pump: DOL or star-deltaSize a 15 kW 400 V pump circuit: cable, breaker, contactor and overload relay. Compare DOL, star-delta, soft starter and drive starts.
- 5 min basahinKitchen power points and the cooktop zonePlace power points and switches near a cooktop, an outdoor gas bottle and a gas vent. Check each distance to AS/NZS 3000 and hand the sink to the wet area tool.
- 3 min basahinMax cable length for a 20 A C curve subcircuitA 20 A curve C socket circuit on 2.5 mm² runs 40 m. See the Zs the engine returns, the Table 8.1 limit and the maximum length before the circuit fails.
- 4 min basahinDownlights in an insulated ceilingRe-insulate a NZ ceiling with downlights in it. Check which may be covered, which only abutted, which must come out, and the clearances and roof space sign.
- 3 min basahinThree‑phase power: kVA to amps at 400 VThe root three relation between amps, kVA and kW on a 400 V board, worked at 50 A and a 0.9 power factor, with the kvar figure the engine returns.
- 5 min basahin12 V caravan cable: d.c. voltage dropA 12 V caravan feed at 30 A over 6 m, checked on 4, 6 and 10 mm² twin against the 10 % ELV limit, then a 48 V battery-to-inverter run.
- 3 min basahinShed earthing on a 16 mm² submainEarth a NZ shed 30 m from the house on a 16 mm² submain. Compare an earth with the submain and a separate MEN with its own rod, and when each is allowed.
- 5 min basahinThree circuits in a hot ceiling: correction factorThree 32 A circuits in conduit across a 40 °C and a 50 °C ceiling space, worked with the NZ 2017 tables and again with AS/NZS 3008.1.1:2025.
- 5 min basahinWhat size breaker for 4 mm² cable4 mm² copper enclosed in air takes a 25 A breaker, and 32 A fails at an Iz of 29 A. Grouping, a hot ceiling, insulation and a long run lower it.
- 4 min basahinRCD arrangement for a house boardCheck a New Zealand house board of eight circuits on two RCDs. See what fails with a fourth circuit on one RCD or both lights on one, and the AU change.
- 4 min basahinTotal voltage drop: mains, submain and finalAdd the voltage drop of the consumer mains, a shed submain and a final subcircuit against the 5 % limit, and fix a long submain before the shed circuits fail.
- 5 min basahinWire a bathroom: zones, IP ratings and the RCDA New Zealand bathroom with a 1.6 m bath and an open shower, worked through the AS/NZS 3000 Section 6 zones, the IP each item needs, the RCD and bonding.
- 6 min basahinAS/NZS 3008.1.1 table numbers: 2017 to 2025Each AS/NZS 3008.1.1 table AmpSize reads, with its 2017 number, its 2025 number and whether its values moved, and one submain that cites both sets.
- 4 min basahinAS/NZS 3008.1.1 vs 3008.1.2: AU and NZ conditionsThe AU part of AS/NZS 3008.1 rates cable at 40 °C air and the NZ part at 30 °C. One 32 A circuit needs 6 mm² in Australia and 4 mm² in New Zealand.
- 4 min basahinAS/NZS 3008 Table 13 (now 3.18): multicore ratingsWhat AS/NZS 3008 Table 13 gives, why the 2025 AU part calls it Table 3.18, how to read its columns into the calculator, and what moved for buried cable.
- 3 min basahinAS/NZS 3008 Table 22 (now 3.33): bunched groupingAS/NZS 3008 Table 22 is the grouping table for bunched circuits, not a temperature table. The 2025 AU part calls it Table 3.33. Read it in the calculator.
- 3 min basahinAS/NZS 3008 Table 27 (now 3.44, 3.45): temperatureAS/NZS 3008 Table 27 corrects a cable rating for the air or soil temperature. The 2025 AU part splits it into Tables 3.44 and 3.45 and re-derives the factors.
- 5 min basahinAS/NZS 3008 vs BS 7671: cable sizing comparedHow BS 7671 and AS/NZS 3000 with AS/NZS 3008.1 size a cable, where they differ, and why a BS current rating never converts into an AS/NZS one.
- 4 min basahinAWG and the NEC for NZ and AU electriciansAWG sizes and the NEC set against AS/NZS 3000 and 3008.1. A gauge converts to mm², but its rating does not, and the NEC 3 % drop figure is only a note.
- 3 min basahinAS/NZS 3000 Table 8.1: max Zs by curve and ratingTable 8.1 max Zs for a 16 A device, by curve. B allows 3.59 Ω, C allows 1.92 Ω and D allows 1.15 Ω. See why, with a 30 m circuit at 0.89 Ω.
- 3 min basahinAS/NZS 3000 Clause 3.6.2: voltage drop limitWhat Clause 3.6.2 governs, how the 5 percent budget splits across mains and subcircuits, and a 25 A run over 35 m that returns 2.6 percent from the engine.
- 4 min basahinCable size for a 32 A single‑phase 25 m runWork through a 32 A single-phase circuit over 25 metres in New Zealand. See every derating factor, the check that sets the size, and the result the tool gives.
- 4 min basahinDomestic maximum demand with Table C1Assess the maximum demand of a New Zealand house from Table C1, group by group, with a worked example that lands on 52.61 A on a single-phase supply.
- 4 min basahinEarth fault loop impedance and maximum ZsWhat earth fault loop impedance measures, how the maximum Zs check works, and a 32 A circuit on 6 mm² over 25 m that lands on 0.67 ohms against a 0.96 limit.
- 3 min basahinVoltage drop with the mV/A·m methodHow the millivolt per amp metre method works, with a 32 A run over 25 metres on 6 mm² copper and the exact drop, percent and maximum length the tool returns.
Mga calculator na ginagamit ng mga guide na ito
- Site cord length calculatorAng pinakamahabang run ng cord o cable na puwede sa construction site.
- Ohm's law at powerAnumang dalawa sa V, I, R at P ay magbibigay ng iba pang dalawa.
- RCD standing leakage budgetGaano karaming standing leakage ang kayang dalhin ng isang RCD.
- Voltage drop calculatorKalkulahin ang voltage drop sa cable run at tingnan ang limit.
- Test schedule para sa switchboardI-print ang board test sheet kasama ang limit ng bawat test.
- Gabay sa kulay ng electrical wireHanapin ang kulay ng wire para sa fixed wiring at cord, luma at bago.
- Cable fault rating calculatorTingnan kung kayang tiisin ng conductor ang fault current.
- PV isolator and earthing calculatorI-rate ang PV array cable, d.c. isolator at earthing.
- Maximum circuit length calculatorPinakamahabang run na pinapayagan ng voltage drop at ng fault loop.
- Pagsusuri ng umiiral na circuitTingnan ang naka-install na circuit: cable, device, drop at Zs.
- Conduit fill calculatorTingnan kung kasya ang cable bundle sa conduit.
- Circuit loading calculatorBilangin ang mga point na kayang dalhin ng final subcircuit.
- Earth fault loop impedance calculatorTingnan ang earth fault loop impedance laban sa maximum Zs.
- Minimum conductor size lookupHanapin ang pinakamaliit na conductor na pinapayagan para sa circuit.
- Paghahambing ng motor starting methodIkumpara ang DOL, star-delta, soft start at drive starts.
- Cable size calculatorHanapin ang pinakamaliit na cable size na pumapasa sa bawat check.
- Motor circuit calculatorCable, breaker, contactor at overload para sa isang motor.
- Power point location checkPower point malapit sa cooktop, gas cylinder, vent o lababo.
- Downlight clearance checkIC, CA90 o Non‑IC: puwede bang dumikit ang insulation sa ilaw?
- Three phase power calculatorI-convert sa pagitan ng power, current, voltage at power factor.
- Outbuilding earthingI-earth ang shed: earth kasama ang submain, o sarili nitong MEN.
- Correction factor calculatorBasahin ang bawat correction factor at ang rating na kailangan ng cable.
- RCD arrangement checkTingnan ang mga circuit kada RCD at ang lighting split.
- Total voltage drop calculatorIdagdag ang drop ng mains, submain at final laban sa 5 %.
- Wet area zones checkerHanapin ang Section 6 zone, IP at RCD malapit sa tubig.
- Imperial cable size converterHanapin ang device rating para sa lumang imperial cable.
- Maximum demand calculatorI-estimate ang maximum demand para sa domestic o non‑domestic loads.